With the emergence of a mobile computing environment, an interface technique has become popular in which an image is recognized by a camera, and content information stored in a computer or a server on a network is used according to information extracted from the recognized image.
In particular, recognition of an image code such as a one-dimensional bar code, a two-dimensional black and white code, or a two-dimensional color code has attracted interest. This is because privacy is less likely to be violated when the image code is used than when biometrics or a wireless tag is used. In addition, a mobile phone or personal digital assistant (PDA) can recognize the image code using a camera embedded therein.
The image code has been conventionally utilized in the distribution sector and product management sector. Furthermore, the image code is widely used in other sectors including wireless-based multimedia content, business card information, advertisement, and online shopping mall access.
In general, the image code is expressed by using a specific pattern, and thus the image code has a fixed shape. As a result, the design of the image code is generally limited. For this reason, the image code may not be very suitable for the medium to which the image code is attached.
Recently, it has become more common that the image code is not only attached to a printing medium such as a sheet of paper but also expressed on a display medium such as a digital television set (DTV), a liquid crystal display (LCD), or a cathode ray tube (CRT). The image code is visually less sophisticated when expressed on a display medium than when a printing medium is used.
If a two-dimensional black and white code composed of patterns and pixels is displayed on a display medium, there is a problem not only in terms of design but also in terms of recognition. That is, the two-dimensional code can express a square pattern, a rectangular pattern, or a circular pattern, and these patterns may be blurred or distorted when they are expressed with pixels of the display medium.
Meanwhile, the display medium may have rectangular-shaped pixels. A boundary line may be present between the pixels. A luminance phenomenon may occur due to backlight, which may result in significantly damaging an image code having a small pattern. Since a CRT screen is not flat but curved, an image code displayed on the CRT is also curved and significantly distorted.